Hello guys and girls, long time lurker and decided to finally create an account and post my first thread.
Last week I bought a Sapphire RX VEGA 56 Pulse from Overclockers.co.uk on an early black friday's deal and so far I have been very happy with it. However yesterday while playing Hellblade Senua's Sacrifice (first time I really stressed the card for some time) I got some crashes. Caused by my 3D device aparently... long story short, I decided it was the single Rail Amps on my PSU, or lack of them, that were causing the instability so I decided so start underclocking and undervolting and testing on Unigine Superposition at 4K Optimized settings to find the Sweet Spot in Performance per Watt and created this lovely *ahem* table on excel for my findings:

There's a general misconception that undervolting Vega increases it's efficiency, something I found wasn't quite right. So I read an article on Tom's Hardware that specified this misconception:

"Does undervolting improve efficiency, then? Yes and no. If you increase Radeon RX Vega 64's power limit, then yes. If you don't, then no.
It's only by raising the card's power limit that the telemetry can identify voltage as a limiting factor and optimally adjust the resulting clock rate to the actual graphics load. The result barely exceeds the default Balanced mode, though. Conversely, manually decreasing the voltage to 1.0V without increasing the power limit lowers efficiency." -Igor Wallossek (Tom's Hardware)

It's quite obvious that the telemetry in these cards is very good at controlling voltages and frequencies, undervolting only really comes into it's own when you start pushing above the default's power limits and clocks.
For underclocking the easiest method is to simply rely on the automatic voltage regulator to do it's job and only change the clock speeds (it's not even necessary to touch the power limits).
The card's efficiency increased as the frequency went down, logically. However it's Sweet Spot is at around 1300Mhz, in my opinion, so, as long as the performance is good enough for you, it looks to be the best frequency to run the card at.
Need some extra performance? just overclock the HBM (something I haven't done yet).

My friend has just bought a laptop with a full size Vega 56 card in it, so (hopefully) the GPU will be running at similar clock speeds. (I am unsure how much wattage the GPU has). He is getting the Acer Predator Helios 500 with 2700 + Vega 56.

This really makes sense, 130W can be handled by a high end Laptop cooling system and apparently the Vega 56 in it is competitive with the Mobile GTX 1070.

I actually run my Vega 56 Pulse (We have the same card yay!) at 1500 Mhz and 1.025V (in my "optimised" mode) and my power usage is around 200-230W depending on the game. In Warframe at higher FPS it does use a bit more than most workloads though. But never really over 230W.

In actuality Vega, when running inside its efficiency zone is almost as efficient as Pascal.

ArbitraryAffectionyeah these Vega 56 from sapphire are quite good, I bet you could go below 1v at that frequency, and reduce power some more. And damn that laptop looks nice, albeit a bit power hungry...MrGenius I know overclocking the memory increases power consumption but at some point it will be more efficient than squeezing some more hz out of the core, supposedly

I think your initial experience is about right 90% of the time my gpu is running at 1v 1499/975 and 180 watts while folding but I don't get why you would limit it unless you game all day and night or like the Op are power constrained , while gaming little on it i run it faster.

Afterburner is good for reference or MSI cards. Pretty much anyway. Though the core voltage control is wonky. +100mV will crash my reference card without fail. +87mV(1187mV) or lower works for the most part on my reference 64. You have to set it in incremental steps according to the voltage lookup tables in the BIOS. Or it doesn't want to work properly. Long story. Not going into it.

EDIT: Here. Figure it out on your own. In Afterburner +100mV = 1200mV = 1.200V...supposedly. And, from what I understand, any tool you use to change the voltages will need an SVI 2 Compliant voltage entered in mV to work correctly.

WattMan is good for nothing...IMO. Except overvolting in combination with the SoftPowerPlay mod. By "overvolting" I mean above the voltages you can normally set with WattMan(as opposed to "overvolting" with Afterburner, which IS NOT overvolting). It's not a very easy thing to do either. But if you do it exactly the right way...it can be done. Long story. Not going into it. Other than that WattMan's just a massively clunky inconvenient POS...IMO. Though it does work if you have the patience to make it work. Which I do not.

SAPPHIRE TriXX 6.5.0 is good for all cards. AFAIK. Especially if you want to setup a custom fan profile. I'm not 100% sure if it's any better than Afterburner as far as voltage. Haven't messed around with it enough yet. What I do know for sure is that overvoltage(beyond +100mV) does not work...on my card anyway. It crashes just like +100mV in Afterburner does.

Wattman is good enough IMO, never had any major problems with it and it allows me to change both P6 and P7 states (don't know if thats possible with msi afterburner os Sapphire TriXX)
For monitoring I use both Gpu-z and FPS Monitor.

moproblems99If your goal is to underclock just follow my table. If you want to overclock 1.1V will take you close to 1650Mhz. After that the benefit of overclocking is reduced as power consumption increases alot. And don't forget to set P6 and P7 at about 0.05V difference ( example P6: 1050mV, P7: 1100mV)